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Symbolic Representations and Analysis of Large Probabilistic Systems
 In Validation of Stochastic Systems
, 2004
"... Abstract. This paper describes symbolic techniques for the construction, representation and analysis of large, probabilistic systems. Symbolic approaches derive their efficiency by exploiting highlevel structure and regularity in the models to which they are applied, increasing the size of the stat ..."
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Cited by 19 (2 self)
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Abstract. This paper describes symbolic techniques for the construction, representation and analysis of large, probabilistic systems. Symbolic approaches derive their efficiency by exploiting highlevel structure and regularity in the models to which they are applied, increasing the size of the state spaces which can be tackled. In general, this is done by using data structures which provide compact storage but which are still efficient to manipulate, usually based on binary decision diagrams (BDDs) or their extensions. In this paper we focus on BDDs, multivalued decision diagrams (MDDs), multiterminal binary decision diagrams (MTBDDs) and matrix diagrams. 1
Symbolic Representations and Analysis of Large State Spaces
 In this Proceedings
, 2003
"... This paper describes symbolic techniques for the construction, representation and analysis of large, probabilistic systems. Symbolic approaches derive their eciency by exploiting highlevel structure and regularity in the models to which they are applied, increasing the size of the state spaces ..."
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Cited by 6 (2 self)
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This paper describes symbolic techniques for the construction, representation and analysis of large, probabilistic systems. Symbolic approaches derive their eciency by exploiting highlevel structure and regularity in the models to which they are applied, increasing the size of the state spaces which can be tackled. In general, this is done by using data structures which provide compact storage but which are still e cient to manipulate, usually based on binary decision diagrams (BDDs) or their extensions. In this paper we focus on BDDs, multivalued decision diagrams (MDDs), multiterminal binary decision diagrams (MTBDDs) and matrix diagrams.
Improving static variable orders via invariants
 In Application and Theory of Petri Nets and Other Models of Concurrency (ICATPN
, 2007
"... Abstract. Choosing a good variable order is crucial for making symbolic statespace generation algorithms truly efficient. One such algorithm is the MDDbased Saturation algorithm for Petri nets implemented in SmArT, whose efficiency relies on exploiting event locality. This paper presents a novel, ..."
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Cited by 4 (3 self)
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Abstract. Choosing a good variable order is crucial for making symbolic statespace generation algorithms truly efficient. One such algorithm is the MDDbased Saturation algorithm for Petri nets implemented in SmArT, whose efficiency relies on exploiting event locality. This paper presents a novel, static ordering heuristic that considers place invariants of Petri nets. In contrast to related work, we use the functional dependencies encoded by invariants to merge decisiondiagram variables, rather than to eliminate them. We prove that merging variables always yields smaller MDDs and improves event locality, while eliminating variables may increase MDD sizes and break locality. Combining this idea of merging with heuristics for maximizing event locality, we obtain an algorithm for static variable order which outperforms competing approaches regarding both timeefficiency and memoryefficiency, as we demonstrate by extensive benchmarking. 1
Activitylocal symbolic state graph generation for highlevel stochastic models
 In Proceedings of the 13th GI/ITG Conference on Measurement, Modeling, and Evaluation of Computer and Communication Systems (MMB
, 2006
"... Abstract. This paper introduces a new, efficient method for deriving compact symbolic representations of very large (labelled) Markov chains resulting from highlevel model specifications such as stochastic Petri nets, stochastic process algebras, etc.. This so called “activitylocal” scheme is comb ..."
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Cited by 4 (2 self)
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Abstract. This paper introduces a new, efficient method for deriving compact symbolic representations of very large (labelled) Markov chains resulting from highlevel model specifications such as stochastic Petri nets, stochastic process algebras, etc.. This so called “activitylocal” scheme is combined with a new data structure, called zerosuppressed multiterminal binary decision diagram, and a new efficient “activityoriented” scheme for symbolic reachability analysis. Several standard benchmark models from the literature are analyzed in order to show the superiority of our approach. 1
Development, analysis and evaluation of performance models for mobile multiagent networks
 Comp. J
, 2006
"... Mobile agents have a number of interesting features such as creation, disposal of agents, execution of services at various network nodes, migration to other network nodes and communication with other agents. Such features are related to the performance area. Based on some examples, scenarios, or cas ..."
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Cited by 3 (0 self)
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Mobile agents have a number of interesting features such as creation, disposal of agents, execution of services at various network nodes, migration to other network nodes and communication with other agents. Such features are related to the performance area. Based on some examples, scenarios, or case studies,Petri netmodels (ordinaryPetri net, coloredPetri net or predicate/transitionnet),mathematical models,simulationmodelsandqueuingmodelshavebeendevelopedintheliterature.Suchresearchworks concentrate on studying the performance of mobile agent networks with much attention on deadlock problems, dynamic behavior problems and the calculation of response time problems. In order to better understandhowtodesigndistributed systemsusing themobile agentparadigmandhow tobuild amodel with thecapabilityof studyingall suchperformanceproblems inaneasyandarealisticway,weproposea newmobile agent performancemodel using the capability of the generalized stochastic Petri net (GSPN) modeling technique. We amended this model with new mobile agent behaviors to fully describe the dynamic behavior of the mobile agent network when it manipulates parallel/multiple agents, and uses some of the most important agent communications (e.g. remote, local, direct, indirect and parallel). Furthermore, the proposed model describes the creation process of new agents during the migration process, theexecutionof tasksamongthenetworknodes, thewayofhandlingtheagentanditsservice task
G.: From symmetric nets to differential equations exploiting model symmetries. The Computer Journal
, 2013
"... Stochastic Symmetric Nets (SSN) are a HighLevel Stochastic Petri Net formalism which provides a parametric system description and an efficient analysis technique that exploit system symmetries to automatically aggregate its states. Even if significant reductions can be achieved in highly symmetric ..."
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Cited by 1 (1 self)
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Stochastic Symmetric Nets (SSN) are a HighLevel Stochastic Petri Net formalism which provides a parametric system description and an efficient analysis technique that exploit system symmetries to automatically aggregate its states. Even if significant reductions can be achieved in highly symmetric models, the reduced state space can still be too large to derive and/or solve the underlying stochastic process, so that Monte Carlo simulation and fluid approximation remain the only viable ways that need to be explored. In this paper, we contribute to this line of research by proposing a new approach based on fluid approximation to automatically derive from an SSN model a set of Ordinary Differential Equations (ODEs) which mimic the system behavior, and by showing how the SSN formalism allows to define an efficient translation method which reduces the size of the corresponding ODE system with an automatic exploitation of system symmetries. Additionally, some case studies are presented to show the effectiveness of the method and the relevance of its application in practical cases.
DESIGN AND EVALUATION OF THE MOD SERVICE SYSTEM BASED ON PETRI NET THEORY
"... AlHefdhi A design for a distributed multimediaondemand (MOD) service system is presented. The MOD system is designed to store, retrieve, and communicate objects comprised of mixed data types including images, text, video, and audio, in realtime. In the MOD system, such data types represent the m ..."
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AlHefdhi A design for a distributed multimediaondemand (MOD) service system is presented. The MOD system is designed to store, retrieve, and communicate objects comprised of mixed data types including images, text, video, and audio, in realtime. In the MOD system, such data types represent the main concept of movie files. To illustrate how to model and analyze the important multimedia aspects of the MOD system, we use the RealNet (Rnet) modeling technique. We choose Rnet as an extension to the Time Petri Net technique due to its ability to specify hard realtime
Modeling Concurrent, Sequential, Storage, Retrieval, and Scheduling Activities of Multimedia Systems
, 2003
"... Abstract. As realtime systems continue to grow, performance evaluation plays a critical role in the design of these systems since the computation time, the service time, and the responsive actions must satisfy the time constraints. One of these systems is the realtime distributed multimediaondem ..."
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Abstract. As realtime systems continue to grow, performance evaluation plays a critical role in the design of these systems since the computation time, the service time, and the responsive actions must satisfy the time constraints. One of these systems is the realtime distributed multimediaondemand (MOD) service system. The MOD system usually fails when it misses a task deadline. The main units of the MOD system usually communicate with each other and work concurrently under timing constraints. The MOD system is designed to store, retrieve, schedule, synchronize, and communicate objects comprised of mixed data types including images, text, video, and audio, in realtime. In the MOD system, such data types represent the main concept of movie files. Modeling of such concurrency, communication, timing, and multimedia service (e.g. store, retrieve) is essential for evaluating the realtime MOD system. To illustrate how to model and analyze the important multimedia aspects of the MOD system, we use the Realnet (Rnet) modeling technique. We choose Rnet as an extension of Time Petri Net due to its ability to specify hard realtime process interaction, represent the synchronization of multimedia entities, describe concurrent multimedia activities, and illustrate the interprocess timing relationships as required for multimedia presentation. Based on modular techniques, we build three Rnet performance models for describing the dynamic behavior of the MOD service system. The first model adopts the Earliest Deadline First (EDF) disk scheduling algorithm. The other models adopt the Scan
Improving Static Variable Orders via Invariants?
"... Abstract. Choosing a good variable order is crucial for making symbolic statespace generation algorithms truly efficient. One such algorithm is the MDDbased Saturation algorithm for Petri nets implemented in SmArT, whose efficiency relies on exploiting event locality. This paper presents a novel, ..."
Abstract
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Abstract. Choosing a good variable order is crucial for making symbolic statespace generation algorithms truly efficient. One such algorithm is the MDDbased Saturation algorithm for Petri nets implemented in SmArT, whose efficiency relies on exploiting event locality. This paper presents a novel, static ordering heuristic that considers place invariants of Petri nets. In contrast to related work, we use the functional dependencies encoded by invariants to merge decisiondiagram variables, rather than to eliminate them. We prove that merging variables always yields smaller MDDs and improves event locality, while eliminating variables may increase MDD sizes and break locality. Combining this idea of merging with heuristics for maximizing event locality, we obtain an algorithm for static variable order which outperforms competing approaches regarding both timeefficiency and memoryefficiency, as we demonstrate by extensive benchmarking.